Fur brush eraser

ABSTRACT

Electrostatic discharge printing apparatus providing a visual image of a preselected pattern to have a level of electrostatic charge and polarity corresponding to a preselected level and polarity of developer particles, wherein a preassigned portion of the visual image is erased by increasing the electrostatic charge on the preselected image portion to exceed the preselected level of the developer particles, and thereafter using other developer particles of the preselected level and polarity to attract thereto the increased charged developer particles of the preselected polarity to erase the preassigned image portion without disturbing the remainder of the visual image having the preselected charge level and polarity.

United States Patent 1 Bresnick [111 3,738,745 June 12, 1973 FUR BRUSH ERASER Herbert L. Bresnick, Rochester, N.Y.

[7 3] Assignee: Xerox Corporation, Stamford, Conn.

[22] Filed: Dec. 30, 1971 [2]] Appl. No.: 213,917

[75 1 Inventor:

52 us. or. ..3ss/17,35s/3 s1 rm. Cl G03g 13/22 [58] FieldoiSearch ass/7,17; 96/l,

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 15,518 5/1966 Japan 355/17 Pimer fi im l ere.

Attorney-James J. R alahatefAlhert A. M ahassel, James C. J angarathis et al.

[ ABSTRACT Electrostatic discharge printing apparatus providing a visual image of a preselected pattern to have a level of electrostatic charge and polarity corresponding to a preselected level and polarity of developer particles, wherein a preassigned portion of the visual image is 'erased by increasing the electrostatic charge on the 9 Claims, 4 Drawing Figures 4/2 22 L l l6 PATENTED 2W3 Prior of Art Document or Pin Electrode Patterns I 9 to be imaged Brush ,4 Applicator or Developer Particles This invention relates to a method of and a device for erasing a visual image in electrophotographic printing apparatus utilizing electrostatic discharges, and more specifically to such device adapted to increase the electrostatic charge of one polarity and level on a preassigned portion of a visual image electrostatically charged to an opposite polarity and lower level for erasing the preassigned image portion without disturbing the remainder of the visual image charged to a lower electrostatic level at the one polarity.

Document reproduction has been heretofore achieved by electrophotographic printing wherein patterns of electrostatic charges are deposited on a suitably charged medium to form latent electrostatic images thereon. Subsequently, electrostatic developer particles moved into contact with such latent images develop the latter into corresponding visual images. Such electrophotographing printing is disclosed in U.S. Pat. No. 3,301,126 issued to R. F. Osborne and assigned to the Xerox Corporation. Electrophotography has also been used in photoprinting systems as disclosed in pending U.S. Pat. application, Ser. No. 887,666, filed on Dec. 23, 1969 and assigned to the assignee of the instant application. Electrophotographic printing devices are known for providing electrostatic latent images on a suitable surface in correspondence with the patterns of selectively activated electrodes. The electrostatic developer particles develop the latent images into corresponding visual images. In the foregoing electrophotographic printing, it is occasionally necessary to erase a group of visual images for replacement with a more suitable group thereof or to erase discrete erroneous visual images for replacement with correct discrete visual images.

The present invention therefore provides an arrangement adapted for use with electrostatic discharge printing apparatus producing a visual image of a preselected pattern, whereby a preassigned portion of the visual image is erased without disturbing the remainder thereof.

A principal object of the present invention is to provide improved electrostatic printing apparatus.

Another object is to facilitate the electric erasure of preassigned portions of electrostatically charged visual images.

Additional objects become readily apparent in the following description.

In combination with electrophotographic printing apparatus comprising an electrode, an electric conductive paper for receiving electrostatic discharges, a member containing a pattern to be copied, voltage means providing an electrostatic discharge to the electrode for forming on the paper a latent image having a preselected polarity and corresponding to the member pattern, and an applicator brush having electrostatic developer particles of a polarity opposite to the image polarity and contacting the latent image to develop the latter into a corresponding visual image having the opposite polarity, wherein a need to change a preassigned portion thereof is apparent; the improvement according to a specific embodiment of the present invention including a supply of direct voltage for superimposing an electrostatic charge of the opposite polarity on the preassigned image portion of the same polarity to provide the latter portion with an increased negative polarity charge relative to the negative charge on the'applicator brush particleswhereby the latter particles are' utilized to attract the increased charge particles thereby erasing the preassigned image portion.

The voltage supply provides a direct voltage of predetermined magnitude and has one terminal of preassigned polarity connected to another electrode which is grounded and supports the paper after removal from the printing apparatus. The voltage supply has another terminal of a polarity different from the one terminal polarity and disposed in proximity of the visual image portion to be erased for enabling the voltage supply to superimpose on the latter portion an electrostatic charge of a magnitude and polarity corresponding to the supply voltage magnitude and the another terminal different polarity, respectively. The smaller electrostatic charge on the developer particles of the applicator brush, which charge is effectively positive relative to the increased charged preassigned image portion, attracts the developer particles of the increased charge from the latter portion to the applicator brush, thereby erasing such portion from the visual image, without disturbing the developer particles of the preselected charge on the remainder of the visual image.

Thereafter, the paper is returned to the electrophotographic printing apparatus which then provides a further electrostatic discharge to the electrode therein for forming on the erased preassigned image portion another latent image corresponding to another pattern for development by the applicator brush developer particles into another visual image portion as a replacement of the erased preassigned visual image portion.

The invention is readily understood from the following description taken together with the accompanying drawing in which:

FIG. 1 is a block illustration of conventional electrophotographic printing apparatus;

FIG. 2 is a plan view taken along line 22 in FIG. 1;

FIG. 3 is a schematic circuit showing the specific embodiment of the invention usable with a portion of FIG. 1; and

FIG. 4 is a fragmentary view of the specific embodiment of the invention in FIG. 3.

FIG. 1 shows conventional electrophotographic printing apparatus 9 including a source 10 of voltage, a member 11 containing a document for reproduction or pin electrodes having alphabetical patterns or the like for recording on electric conductive paper 12, and an electrode 13 supporting the paper and connected to ground. An applicator 14 supplies electrostatic developer particles to the paper. The apparatus operates to provide an electrostatic discharge to the electrode to form on the paper a latent image having a preselected polarity and corresponding to the document or the pin electrode patterns. Subsequently, the applicator supplies electrostatic developer particles which have a polarity opposite to the latent image polarity and which contact the latent image'to develop the latter into a corresponding visual image having the opposite polarity. At this time, a need for a change in a given portion 15 of the visual image may be instantly apparent. This change may involve up-dating the document in the given portion thereof or correcting an error in the spelling of a word in the case where pin electrode patterns are imaged on the paper. It is understood that the latent image may have either positive or negative polarity while the developer particles have a polarity opposite to the preselected latent image polarity.

The foregoing conventional electrophotographic apparatus is shown and described in its briefest form for the purpose of simplifying the disclosure. This is readily understood by one of ordinary skill in the art. One illustration of documentary reproduction via the use of electrostatic discharge is disclosed in the Osborne patent, supra. One illustration of reproducing pin electrode patterns is disclosed in patent application of Howard Ring, Ser. No. 214,300, filed Dec. 30, 1971.

A specific embodiment of the invention in accordance with FIG. 3 comprises an erasing device 20 including a supply 21 of direct voltage of a predetermined magnitude say, for example, 400 volts. This supply has a preselected positive terminal connected via lead 22 to electrode 16 and a negative terminal extended via lead 23 to a probe 24 for effective disposition in proximity of the given portion of the visual image on the paper as subsequently explained.

FIG. 4 shows probe 24 consisting of an elongated insulating handle 30 supporting at one endlead 28 and terminating at an opposite end in a brass tubular insert 31 which is connected to the latter lead at point 32. This insert, fitted with a group of metallic fibers 34 including, for example, stainless steel material, has corresponding contiguous fiber ends mounted firmly inside the brass insert and opposite corresponding contiguous ends projecting therefrom for a purpose hereinafter mentioned. It is understood that the probe is light in weight to permit expeditious manipulation thereof for a purpose later explained.

The operation of the invention in FIGS. 3 and 4 takes place in the following manner. The given portion 15 of the sheet 12 in FIG. 2 is assumed to comprise a visual word AN which is to be erased and replaced in the documentary reproduction with another visual word T0, not shown, for the purpose of this description. Obviously, the visual image portion to be erased may comprise a longer word or a group of words to change the language of the document as required. On the other hand, when the patterns of pin electrodes are imaged on the paper in response to human control, an error in the spelling of a word may occur. Correction of such error may involve erasure and replacement of one letter in the word, or quite possibly erasure and correction of the entire word. In the example of the given portion 15 in FIG. 2, the correct work ON, not shown, may have been intended, thereby requiring an erasure of the letter A and the replacement thereof with the letter O. It is also assumed that the latent image AN had initially a preselected positive polarity while the developer particles supplied by applicator 14 had a negative polarity, whereby the visual image AN is provided with an electrostatic charge level and polarity corresponding to a preselected electrostatic charge level and polarity of the developer particles at the applicator thereof.

Next, the paper is removed from the electrode 13 in the electrophotographic printing apparatus and positioned on electrode 16 in FIG. 3. Then, the free ends of the stainless steel fibers of the probe are disposed in proximity of the visual word AN on the given paper portion 15, whereupon an electrostatic charge of negative polarity is superimposed on the already negatively charged visual word AN. The magnitude of the superimposed negative electrostatic charge corresponds approximately to the predetermined magnitude of 400 volts provided by the supply 21. This renders the visual word AN more negatively charged than the remainder of the visual image on the paper and the negatively charged developer particles supplied thereto by the applicator.

Now, the paper in such differently negatively charged state is repositioned on the electrode 13 in the electrophotographic printing apparatus and thereby subjected to the action of the developer particles on the applicator brush. As these particles are less negative, i.e., positive relative to the heavily negatively charged visual word AN, the increased negatively charged developer particles on the visual word AN, are attracted by the less negatively charged, relatively positive polarity, developer particles on the applicator, whereby the visual word AN iserased from the given paper portion 15 to leave a vacant spot thereat. Since, at the same time, the remainder of the visual image is negatively charged to the level of the charge on the developer particles at the applicator, the state of such remainder visual image is unaffected by the erasing action of the applicator particles as just mentioned. In a similar manner, the letter A is erased from the word AN. It is thus seen that electrostatically charged developer particles of effective negative polarity are attracted to electrostatically charged developer particles of positive polarity to erase the unwanted portions from the visual image. It is understood that the invention operates equally as well when the polarities of the latent image, visual image and probe are reversed from those hereinbefore mentioned.

Subsequently, the paper as repositioned on the electrode 13 in the electrophotographic printing apparatus is provided in the vacant spot is with the replacement visual word T0 or the replacement visual letter O in the manner hereinbefore explained. It is thus seen that the applicator serves two purposes, viz., initially, to apply developer particles of a preselected electrostatic charge level and a preselected polarity to the latent image to develop the latter into a visual image, and secondly, to erase the unwanted word or letter without deleteriously affecting the remainder of the visual image on the paper. It is understood that the invention may also be utilized with electrostatic discharge printing apparatus wherein the erasure of unwanted words or letters can be effected without removing the paper therefrom.

It is understood that the invention herein is described in specific respects for the purpose of this description. It is also understood that such respects are merely illustrative of an application of the invention. It is obvious that while the invention is hereinbefore described with reference to specific electrostatic discharge apparatus, it is readily applicable to use with electrostatically charged visual images obtained from other apparatus. Numerous other arrangements may be derived by one of ordinary skill in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In combination with electrostatic printing apparatus including means for deriving an electrostatic latent image of a preselected pattern, and a supply of developer particles having a preselected level of electrostatic charge and a preselected polarity for providing said developer particles to develop said latent image into a visual image having a-level of electrostatic charge and a polarity corresponding to said preselected level and said preselected polarity respectively;

means for erasing a preassigned portion of said visual image, comprising:

voltage means for increasing said electrostatic charge on said developer particles in said preassigned image portion to a level exceeding said preselected electrostatic charge level, said voltage means including a source of direct voltage having such level as to provide said increase of exceeding level in said electrostatic charge on said developer particles in said preassigned image portion whereby said increased charge level is provided with a polarity coincident with said preselected polarity;

said supply providing additional developer particles having said preselected electrostatic charge level and said preselected polarity whereby said developer particles of increased electrostatic charge are attracted from said preassigned image portion to said supply to erase said last-mentioned portion from said visual image, without disturbing said developer particles having said preselected charge level and said preselected polarity on the remainder of said visual image.

2. The combination according to claim 1 in which said source has positive and negative terminals of which a predetermined one of said terminals is applied to an undersurface of said visual image and the other of said terminals is disposed in proximity of said preassigned image portion for providing an electrostatic discharge from said source to said last-mentioned portion to increase the level of said electrostatic charge on said certain developer particles in said preassigned image portion.

3. The combination according to claim 2 which includes electric metallic brush means for disposing said source other terminal in proximity of said preassigned image portion.

4. The combination according to claim 3 in which said brush means includes one end connected to said source other terminal and an opposite end formed with a group of metallic fibers having contiguous ends immovably mounted in said last-mentioned opposite end and adjacent opposite ends disposed in proximity of said preassigned image portion.

5. The combination according to claim 4 in which said metallic fibers comprise stainless steel.

6. The combination according to claim 1 in which said source of direct voltage includes:

positive and negative terminals and a level adequate to provide said increase of exceeding level in said electrostatic charge on said developer particles in said preassigned image portion; and

circuit means for connecting a preselected one of said terminals to an undersurface of said image and disposing the other of said terminals in proximity of a surface of said image including said preassigned portion for providing an electrostatic discharge from said source to said preassigned image portion to increase said electrostatic charge on said developer particles in said preassigned image portion to said exceeding level; said circuit means consisting of:

a group of metallic fibers having contiguous ends connected to said source other terminal and oppo- 5 site free adjacent ends disposed in proximity of said preassigned image portion to provide said lastmentioned electrostatic discharge.

7. In combination with electrophotographic printing apparatus, including:

a preselected pattern, electrostatic discharge means for deriving a latent image of said pattern, and a supply of developer particles having a preselected level of electrostatic charge and a preselected polarity for providing certain of said developer particles to develop said latent image into a visual image having a level of electrostatic charge and a polarity corresponding to said preselected level and preselected polarity of said certain developer particles;

means for erasing a preassigned portion of said visual image, including:

a source of direct voltage having a predetermined level and negative and positive terminals;

circuit means for connecting a predetermined one of said terminals to an undersurface of said visual image; and

a brush of metallic fibers having contiguous ends connected to the other of said source terminals and opposite adjacent ends disposed in proximity of said preassigned image portion for producing an electro-static discharge from said source to said last-mentioned portion to in-crease said level of electrostatic charge on said certain developer parti-cles in said preassigned image portion to exceed said preselected electrostatic charge level of said certain developer particles as provided at said supply whereby said exceeding electrostatic charge level has a polarity coincident with said certain developer particles;

said supply providing other developer particles having said preselected electrostatic charge and preselected polarity for attracting said certain developer particles of increased electrostatic charge from said preassigned image portion to said other developer particles to erase said preassigned image portion from said visual image, without disturbing said certain developer particles having said preselected electrostatic charge level and preselected polarity on the remaining portion of said visual image.

8. In an electrostatic printing process wherein a developed image is formed by the application of an electrostatic developer including charged toner particles of a first polarity to an electrostatic latent image, the method of erasing at least a portion of said developed image, comprising the steps of: 7

increasing the charge exhibited by the charged toner particles of said first polarity on said portion of said developed image; and

reapplying said electrostatic developer to said developed image to electrostatically attract said increased charged toner particles on said portion of said developed image to said electrostatic developer.

9. The method of claim 8 wherein said step of increasing the charge exhibited by said charged toner particles comprises the step of applying a voltage potential of said firstpolarity and of predetermined magnitude to said charged toner particles.

i l IR l 

1. In combination with electrostatic printing apparatus including means for deriving an electrostatic latent image of a preselected pattern, and a supply of developer particles having a preselected level of electrostatic charge and a preselected polarity for providing said developer particles to develop said latent image into a visual image having a level of electrostatic charge and a polarity corresponding to said preselected level and said preselected polarity respectively; means for erasing a preassigned portion of said visual image, comprising: voltage means for increasing said electrostatic charge on said developer particles in said preassigned image portion to a level exceeding said preselected electrostatic charge level, said voltage means including a source of direct voltage having such level as to provide said increase of exceeding level in said electrostatic charge on said developer particles in said preassigned image portion whereby said increased charge level is provided with a polarity coincident with said preselected polarity; said supply providing additional developer particles having said preselected electrostatic charge level and said preselected polarity whereby said developer particles of increased electrostatic charge are attracted from said preassigned image portion to said supply to erase said last-mentioned portion from said visual image, without disturbing said developer particles having said preselected charge level and saId preselected polarity on the remainder of said visual image.
 2. The combination according to claim 1 in which said source has positive and negative terminals of which a predetermined one of said terminals is applied to an undersurface of said visual image and the other of said terminals is disposed in proximity of said preassigned image portion for providing an electrostatic discharge from said source to said last-mentioned portion to increase the level of said electrostatic charge on said certain developer particles in said preassigned image portion.
 3. The combination according to claim 2 which includes electric metallic brush means for disposing said source other terminal in proximity of said preassigned image portion.
 4. The combination according to claim 3 in which said brush means includes one end connected to said source other terminal and an opposite end formed with a group of metallic fibers having contiguous ends immovably mounted in said last-mentioned opposite end and adjacent opposite ends disposed in proximity of said preassigned image portion.
 5. The combination according to claim 4 in which said metallic fibers comprise stainless steel.
 6. The combination according to claim 1 in which said source of direct voltage includes: positive and negative terminals and a level adequate to provide said increase of exceeding level in said electrostatic charge on said developer particles in said preassigned image portion; and circuit means for connecting a preselected one of said terminals to an undersurface of said image and disposing the other of said terminals in proximity of a surface of said image including said preassigned portion for providing an electrostatic discharge from said source to said preassigned image portion to increase said electrostatic charge on said developer particles in said preassigned image portion to said exceeding level; said circuit means consisting of: a group of metallic fibers having contiguous ends connected to said source other terminal and opposite free adjacent ends disposed in proximity of said preassigned image portion to provide said last-mentioned electrostatic discharge.
 7. In combination with electrophotographic printing apparatus, including: a preselected pattern, electrostatic discharge means for deriving a latent image of said pattern, and a supply of developer particles having a preselected level of electrostatic charge and a preselected polarity for providing certain of said developer particles to develop said latent image into a visual image having a level of electrostatic charge and a polarity corresponding to said preselected level and preselected polarity of said certain developer particles; means for erasing a preassigned portion of said visual image, including: a source of direct voltage having a predetermined level and negative and positive terminals; circuit means for connecting a predetermined one of said terminals to an undersurface of said visual image; and a brush of metallic fibers having contiguous ends connected to the other of said source terminals and opposite adjacent ends disposed in proximity of said preassigned image portion for producing an electro-static discharge from said source to said last-mentioned portion to in-crease said level of electrostatic charge on said certain developer parti-cles in said preassigned image portion to exceed said preselected electrostatic charge level of said certain developer particles as provided at said supply whereby said exceeding electrostatic charge level has a polarity coincident with said certain developer particles; said supply providing other developer particles having said preselected electrostatic charge and preselected polarity for attracting said certain developer particles of increased electrostatic charge from said preassigned image portion to said other developer particles to erase said preassigned image portion from said visual image, without disturbing said certain developer particles haviNg said preselected electrostatic charge level and preselected polarity on the remaining portion of said visual image.
 8. In an electrostatic printing process wherein a developed image is formed by the application of an electrostatic developer including charged toner particles of a first polarity to an electrostatic latent image, the method of erasing at least a portion of said developed image, comprising the steps of: increasing the charge exhibited by the charged toner particles of said first polarity on said portion of said developed image; and reapplying said electrostatic developer to said developed image to electrostatically attract said increased charged toner particles on said portion of said developed image to said electrostatic developer.
 9. The method of claim 8 wherein said step of increasing the charge exhibited by said charged toner particles comprises the step of applying a voltage potential of said first polarity and of predetermined magnitude to said charged toner particles. 